Vésigniéite

Milpillas mine

Cuitacas

Municipio de Santa Cruz

Sonora

Mexico

5.7 by 2.0 by 2.0 cm – Miniature specimen (fits into a 5 cm cube)

Vésigniéite is a rare hydrated barium copper vanadate. Guillemin (1955) named this mineral in honor of Colonel Jean Paul Louis Vésignié (1870-1954), a French mineral collector. This material was first noted by Peter Megaw, as bronzy plates with pseudomorphous malachite in 2008. Single crystal methods at the University of Arizona identified the mineral. Vésigniéite at Milpillas typically forms loose stacks of platy crystals, here to 7 mm. These platy aggregates likely represent pseudomorphs after primary volborthite. Quite large for the locality. Could be trimmed into a thumbnail specimen.